It is the objective of the proposed investigation to identify risk factors and prognostic factors for ovarian cancer. This interdisciplinary study will cover several epidemiological factors, hormones (e.g. LH, FSH estrogens, gestagens, inhibin and activin, and different biochemical markers (e.g. tetranectin and CA 125). Cases consist of women (40-79 years of age), who are diagnosed with tumor ovarii in a 3- year period. All hospitals in Greater Copenhagen as well as the larger hospitals on Sjaelland will be potential participants. In this study area, about 260 new cases of ovarian cancer will appear every year. These will be included in the study together with a random sample of the benign tumors which also are covered by the inclusion criteria. When a woman is admitted to one of the hospitals in the study area to an operation for tumor ovarii, pre-operative blood samples are taken and mailed to the Serum Institut. Simultaneously, a form is filled out with the patient's name, cpr-number and operation date. This form is mailed to the Danish Cancer Registry. About 3 days after the operation, the hospital department is contacted by the secretariat of the ovarian cancer study (placed at the Danish Cancer Registry) in order to schedule the patient for a personal interview at the hospital department. From the same geographical area (Sjaelland), an age-matched sample of women will be drawn at random from the Central Population Register. Two healthy control women are drawn at random to match each case. These controls will be interviewed and have blood samples taken in their homes. All the blood samples will be sent to Statens Seruminstitut, where they will be separated into serum, plasma, buffy coat and aa filter paper blood sample. All is kept deep frozen at -80 degrees C until tested. The collaborating pathologist will review all archival material blindly. Follow-up About 2 months post-operatively, the secretariat will write for descriptions of the operation and the pathology. The above-mentioned descriptions will form the basis of the staging of the ovarian cancer. The judgement of stage will be conducted independently by two gynecologists. The ovarian cancer group will be followed with regard to course or disease and death. In conclusion, it is the aim of the study to establish a biological bank including blood samples (preoperative) from ovarian cancer patients and from a random sample of normal women (same geographical area and age-group) as well as an information bank including information on various life-style factors and environmental exposures. These banks will form the basis for studies of risk determinants, prognostic factors and biochemical markers.